Variable speed gear



Aug. 9, 1938. A. TIMMERMANN 2,126,294

- VARIABLE SPEED GEAR Filed July 26, 1937 4. Sheets- Sheet 1 Tali-DRIVING v n V V SHAFT-1 INVENTOR 3171 41 5,};nWM BY %0/ @AT ORNEYS ,1 8-A. TIMMERMANN 2,126,294

VARIABLE SPEED GEAR Filed July 26,1937 4 Sheets-Sheet 2 V W \l //V W 5%,1; ORNEYS Aug. 9, 1938.- A. TIMMERMANN 2,126,294

VARIABLE,SPEED GEAR Filed July 26, 1937 4 Sheets-Sheet s INVENTOR .fi' ATORNEYS Aug. 9,1938. A. TIMMERMANN VARIABLE SPEED GEAR Filed July 26,1937 4 Sheets-Sheet .4

- INVENTCR W9I/XIWM w I MA Z ORNEYS Patented Aug. 9, 1938 UNlTED STATESPATENT OFFICE,

7 Claims.

My invention relates to a type'of variable speed planetary gear drive inwhich all gears remain in mesh at all times, the variation in speedbetween the driving and the driven shafts being effected by controllingthe speed of the control gear which surrounds, the planetary wheels in.a. particularly novel manner.

a The present invention in particular is an improvement on the controlwheel drive disclosed in U. S. Patent No. 2,076,926, granted to me onApril 13, 1937, the planetary gear arrangement per se being in substancesimilar to that shown in the aforementioned patent.

My invention is illustrated in the accompanyingdrawings in which Figure1 represents a longitudinal sectional elevation of the entire geardrive. I

Figure 2 represents an end elevation, partly in section on the line 22in Figure 1 Figure 3 represents in longitudinal sectional elevation amodified form of the gear drive shown in Figure 1, and

Figure 4 represents an end elevation, partly in section, .on line, 2-2of Figure 3,'the outer casing being omitted.

The present application constitutes a continuation in part of myapplication for variable speed gear, Serial No. 129,537, filed March 8,1937, and allowed July 8, 1937, the subject matter of said applicationbeing fully embodied in Figures 1 and 2 of the present application.Figures 3 and 4 of the present application, though involving broadly thesame principle as Figures 1 and 2. show a modified and simplified formin which the novel idea may be reduced to practice, and constitute thefurther development of the principle embodied in Figures 1 and 2 of theearlier application.

It is the particular purpose of the present invention to simplify themanner in which the speed of the control wheel, denoted I3 in Figure lof my aforementioned patent, is varied. Especially it is the purpose ofthe present invention to avoid in such a speed control any outside drivethrough gears or belts, such as is shown in aforesaid patent, and toconfine this speed control to an arrangement located within the compassof the control wheel or'gear, so that the entire planetary gear drivemay be enclosed within a comparatively small casing.

Referring to Figure 1, I is the driving shaft which is journalled in thegear box 2 by way of a central, inwardly extending sleeve 3 and ballbearings 4. Of course, if desired, roller bearings may be substituted inthe present case for the ball bearings in all cases where convenient.The driven shaft 5 is journalled in axial alignment with the drivingshaft I in the other end of casing 2 by means of ball bearings 6, theinner end of shaft 5 being journalled in the inner. end of drive shaft Iby means of ball bearing I. The inner end of the driven shaft carriestwo pinions 8, spaced apart and of equal pitch and construction, and ofwhich the left-hand gear may, for instance, constitute an integralportion of shaft 5, while the right-hand pinion is attached to the shaftend by any suitable means known in the art of motor vehicleconstruction. such as cones, keys, square shaft ends or the like. On thedriven shaft 5 is journalled by means of ball bearings 9 a yoke Illfreely rotatable thereon and provided with two diametrically oppositedisposed studs II which form the bearing for two planetary gears I2.These planetary gears are each provided with a central outer peripheralbead I3 which divides the outer gearing of these wheels into twoperipheral halves. This central peripheral bead engages between the twopinions B on shaft 5, thereby forming a lateral support for planetarygears I2. The bead has a diameter sufliciently large so as to roll onthe portion of shaft 5 located between the pinions 8, therebymaintaining the'proper depth of mesh between the teeth of the pinions 8and of the planetary wheels I2. These planetary wheels are encircled bya control gear wheel l4, the teeth of which are separated in axialdirection so that they form two groups We and I6b, spaced apart thedistance of head I3 of planetary wheels I2 so that this bead I3 becomeslocated between these two. groups of teeth when the teeth are in meshwith the planetary gears I2.

To the end of driving shaft I is keyed as shown at Ila, a. yoke II whichhas two oppositely disposed studs I8 extending into the interior ofplanetary gears I2 and which carry at their ends each a roller I5.The'inner periphery of each of planetary wheels I2 is provided with agroove .20 which extends into the bead I3 of each wheel slightly belowthe pitch circle of the wheels, and the aforementioned rollers I9 arelocated in these peripheral grooves, so that when driving shaft Irotates, planetary wheels I2 are taken along with the tendency to rotatethe 1 control wheel. I4 inopposite direction. In the present casethe'control wheel I4 is journalled at 2| freely rotatable on the sleeveIlla of the afore-described yoke ID. A spacing collar 22 is providedbetween the sleeve Illa and the end of easing 2. Thus according towhether control wheel l4 rotates at the same speed as driving shaft I,or rotates faster, the speed of the driven shaft will vary in the mannerdescribed in my aforementioned patent.

The speed .of control wheel I4 is varied and is prevented fromrotatingin a direction opposite to driving shaft I in the followingmanner. Control wheel l4 has a cylindrical extension l4a which forms acylindrical casing, and which carries on its inner periphery twoserrated overrunning clutch rings 23a and 23b, spaced apart and confinedbetween an inner peripheral ridge 24 of casing Na and the cover 25'ofthe casing. These overrunning clutch rings are centered in theconventional manner by rollers 26, which are located between theserrations of the rings and which bear against the inner periphery ofcasing Ha, as shown more clearly in Figure 2. The two overrunning clutchrings 23a and 23b are held apart by two diametrically opposite disposedpinions 21 which mesh with the lateral faces of clutch rings 23a and23b. These pinions 21 are mounted rotatably each on an arm 23 keyed at30, to a stud 29 mounted on yoke 11. Thus assuming for the moment thatdriving shaft 1 stands still, one clutch ring will rotate in onedirection, or tend todo so if the other clutch ring is rotated in theother direction. For instance,

. if in Figure 2 which shows in the upper half clutch ring 23b inelevation and in the lower half clutch ring 23a partly in section andpartly in elevation, clutch ring 231) should be rotated clock-p wise,the rollers 23 of this clutch ring will engage casing l4a and take thiscasing along clockwise. At the sametime, due to pinions 2'I clutch ring23a will be moved counterclockwise and there- .fore run free withincasing l4a. On the other hand, if clutch ring 23a should be rotatedclockwise, its rollers 26 would engage casing Ma and clutch ring 23bwould be rotated counterclockwise and thus be disengaged from casing Ma.

The manner in which these'two overzunning clutch rings are alternatelymoved into engaging position with casing Ma and are driven thereby ata-speed at which it is desired to drive casing Na and thus control wheel[4, is as follows. The aforementioned studs 29 besides carrying thefixed arms 23, also carry each a gear sector 3m and 3lb respectively.Gear sector 3la meshes with an internal toothing 48 of clutch ring 23a,

which toothing extends only over' a limited arcuate distance, dependingon the number of teeth in sector3la. Gear sector 3") meshes withaninternal toothing 43 provided on clutch ring 2311, and which toothingextends similarly over only a limited distance. Each of these gear.sectors is provided with an extension 32b and 32a respectively, each ofwhich carries a cam roller 33 which 1 rolls on a coneesha'ped cam 34splined-by means three, on cam 34 so that when the cam roller 33 of onegear sector (for instance 3lb) is at one of the low points of the cam,the roller 33 of the other gear sector (3la) will be at or near one ofthe high points of the cam.

This arrangement operates as follows: Let us assume that yoke llon thedriving shaft I rota es in clockwise direction, as shown in Figure 2 bythe arrow a. In the position. shown in Figure 2, roller 33 of gearsector 3"; is about to ride from one of the low points on cam 34 towardthe high point 34b, while cam roller 33, as aforementioned,

has arrived on the high point 34a of cam 34. As yoke l'i continues inclockwise direction, and as roller 33 rides towards the high point 34b,gear sector 3lb is rotated clockwise on its stud 29 and thereby alsorotates clutch ring 235 clockwise but 'at an angular speed greater thanthe angular speed at which yoke I1 rotates. As clutch ring 23b inrotating clockwise engages the control wheel casing No, this casing,together with control wheel i4, will be taken along at this increasedspeed. Thus by the time roller 33 of sector 3Ib has'arrived at the top34b of cam 34, clutch ring 23b and thus control wheel l4 has run aheadof yoke il, an angular distance approximately equal to the number ofteeth engaged by sector 3), depending upon the height of the high point34b of the cam. At that moment sector 3i will be in angular positionwith respect to its stud, similar to the position in which gear sector3Ia is shown in Figure 2, whose roller 33 has Just arrived at the highpoint 34a of the cam 34. The contour of the three-lobed cam 34 isdesigned so that the roller 33 of gear sector 3; starts its ascenttowards the next high point at a time when roller 33 of sector 3l,a isjust over the high point. When clutch ring 23b, as aforedescribed, isthus rotated bygear sector 3ib clockwise ahead of the driving yoke ll,it also rotates plnions 21 which are also in mesh with clutch ring 23a,thereby rotating in the manner aforedescribed, this latter clutch ringcounterclockwise so that itfrees itself from engagement with casing Maand takes along with it gear sector 3la in counterclockwise direction.Thereby the roller 33 of gear sector 3Ia rolls down toward the next lowpoint of cam 34. As yoke llcontinues rotating in clockwise direction,now roller 33 of gear sector 3la rolls toward the next high point of cam34 while roller 33 of gear sector 3|b rolls off high point 34b of cam34. Now gear sector 3la advances-clutch ring 23a in clockwise direction,whereby control wheel casing l4a is taken along and continues runningahead of yoke II, while through pinlons 2'I clutch 7 ring 23b isdisengaged from casing Ma and returns into the position in which it isshown in Figure 2. This forward and backward play of gear sectors- 3Iaand 3|b continues so long as rollers 33 alternately engage high and lowpoints of cam 34.

Cam 34 is designed so that its highest highpoints are located near theright-hand end in Figure 1, and its lowest high-points are located nearthe left-hand end; in fact, near the left-hand end of the cam there arepractically no relative high points, the cam being cylindrical at thatpoint (34c, d), and the angular position of each of sectors 3m and 3lbwould be about midway between the extreme positions of the two gearsectors shown. in Figure 2. For this reason, it will be noted, the leftend points of cam 34 are shown of equal height, whereas near the,righthand end of cam 34 the highest high-point is considerably higherthan the'left-hand low point 34d, while the lowest low-point 34c of thecam is considerably lower than the left-hand low point 340. Thisarrangement is necessary in order to keep at all times the cam rollersin contact with It will thus be observed that as cam '34 is shifted tothe right and the high points of the cam become lower and lower, thegear sectors Ma and 311) will perform smaller and smaller angularmotions and therefore advance the overrunning clutch rings 23a and 23!)smaller and smaller angular distances over the yoke l1 and driving shafti, until when all rollers are at the low point and gear sectors 3la and3") stand still on their respective studs, control casing Ma and thuscontrol wheel M are rotated at the same speed as driving shaft l andthus the driven shaft 5 is rotated at the same speed. On the other hand,when the control wheel M in the manner aforedescribed, runs its maximumangular speed ahead of yoke l1, the driven shaft 5 will run at reversespeed with respect to driving shaft l, and if the cam stands at somepoint between its extreme end positions, control wheel It runs at aspeed which causes driven shaft 5 to stand stillthe gear is in neutral.

While I have shown in the drawings only two gear sectors 31a. and MD, asmany gear sectors and overrunning clutchrings may be mounted withincontrol wheel casing I ia. as may be conveniently placed. In that case,of course also the shape of cam 34 must be correspondingly changed.

The bell crank 35 through which cam 34 is operated, protrudes through aslot provided in cover M of the stationary gear casing, so that it canbe conveniently handled.

The underlying idea involved in the present.

invention, as broadly set forth in the annexed claims 1 and 2, may alsobe reduced to practice in a modified and simplified form, shown inFigures 3 and 4. In these figures, l'again represents the driving shaftjournalled in a sleeve M of casing 43 by means of two bearings 45 and 45provided at the two ends of said sleeve. The driven shaft 5, which isdisposed in axial alignment with the driving shaft, is journalled at itsinner end within the inner end of driving shaft 8 by .means of a'bearing 1, and it is also journalled in casing 43 by I means of abearing 47. The driven shaft, similar to the manner shown in Figure 1,has mounted on it the sun wheel 8 arranged in two halves axially spacedapart so as to provide a groove within which the planetary ring gears 54are guided, these ring gears meshing with the corre sponding sun wheelportions in a manner similar. to that shown and explained in myaforementioned U. S. Patent No. 2,076,926. Similar to the manner alsoshown in this patent, these ring gears areprovided with a centralperipheral groove 55' in which engagev driving rollers 53 rotatablymounted on two diametrically opposite studs 52 provided on head 5! ofdriving shaft I. The outer ends of studs 52 are secured to a holdingring 55 journalled by means of a bearing 57 on the driven shaft 5. T

Planetary rings 55 are surrounded by and in mesh with control gear 58which for that purpose isprovided with .a split inner toothing 58a and aguide groove similar to the manner shown in Figure 1 of the presentapplication.

Control gear 58 is extended in axial direction and provided in thisextension with a wide inner peripheral bead 59 by which it is rotatablymounted on a disc 50, keyed at 6! to the driving shaft head 5!. Thisbead 59 is secured in axial direction on disc 60 between aperipheralshoulder 53 and a retaining ring 62.

So far as described, this arrangement operates similar to the mannerdescribed with reference to Figures 1 and 2, namely, when the driving.shaft 58 has a cylindrical extension 64 which forms a cylindrical casingand which carries on its inner periphery two serrated overrunning clutchrings 55 and whose teeth are pitched in the same direction; the ringsbeing spaced apart by means of a spacing ring 61 and confined rotatablybetween an inner peripheral ridge B8 on casing 64 and retaining ring 69.These overrunning clutch rings are centered in the'conventionalmanner byrollers 26 which are located between the serrations ofthe rings andwhich bear against the inner periphery of casing 64, as shown clearly inFigure 4, in which clutch ring 65 is visible in the upper half of thefigure and clutch ring 65 in the lower half. As will appear more clearlyin Figure 4, clutch ring 65 is provided with a short inner peripheraltoothed portion 10 of a few teeth, for instance five in the presentcase, and clutch ring is provided diametrically opposite from thetoothed portion "I of the clutch ring 55 with a similar number of innerperipheral teeth -'ll. These two toothed segment portions meshvrespectively with toothed sectors 12 and 13 which are each rotatablymounted on a stud 114- provided on disc 50 sothat these toothed sectorsare bodily rotated with the driving shaft I. Assuming for a moment thatboth sectors 12 and 13 are held fast on their pivotal point and assumingfurther that the driving shaft and thus disc '60 rotates'in thedirection of the arrow A in Figure 4,

both overrunning clutch rings 55 and 66 will be relative speed betweenthe driving shaft and control wheel 58, the aforementioned sectors 12and 13' are each pivotally attached at 15 and 16 respectively to anindividual eccentric ring Ti and I8 respectively. These eccentric ringsare mounted on a common eccenter disc 19 by means of ball bearings and8i respectively. The eccentricity of eccenter disc 19 can be varied withrespect to the central axis of driving shaft I by means of a slidingblock 82 slidingly mounted on casing sleeve 44 in axial direction andprovided at diametrically opposite sides with inclined sliding surfacesparallel to one another but pitched at an angle with respect to the axisof driving shaft I, so thatwhen' sliding block 82 is moved axially inone or the other direction, the eccentricity of rings 11 and 18 can beset to a maximum value, such as isshown in Figure 3, or by shiftingblock 82 gradually to the right, the eccentricity"-can be lessened untilin the extreme righthand position of block 82 the eccentricity of areset for their maximum eccentricity, eccentric rings I1 and I8 will causetheir respective sectors I2 and 13 to rock on their pivotal supports 14.This has-the following effect: In Figure 4, the pivotal point 16 atwhich eccentric ring 18 is attached to'seotor I3, is nearest the centerof driving shaft I. If now the driving shaft together with disccontinues to rotate in the direction of the arrow A, the radius betweenthe center of the driving shaft and pivotal point 16 will graduallyincrease whereby sector 13 will be rocked in the direction of the arrowattached to that sector. Thereby clutch ring 66 through its, gear teethII will be moved in the direction of the arrow ahead of the rotationspeed of driving shaft I. Thereby clutch ring II through the rollers 26engages the cylindrical casing 64 of the control wheel 58 and thusrotates the latter ahead of the driving shaft I an angular distanceapproximately equal to the number of teeth engaged by sector I3, whichin turn depends upon the angle through which sector I3 moves. At thesame time when eccentric ring 18 operates gear sector 13 as'described,eccentric ring 11 rotates sector 12 in the direction of the arrow markedon that sector and thereby moves clutch ring 65 in the direction of thearrow, i. e. oDDOsite to the direction in which clutch ring 'II ismoved. Clutch ring can be freely moved in that direc ticn owing to theconstruction of the overrunning clutch rings. As soon as sector 13 hascompleted its advance ofits clutch ring II, sector I2 has completed thecounterclockwise retardation of its clutch ring 65 and the eccentricrings now move the sectors I2 and I3 respectively in opposite direction,namely, sector 12 is then moved clockwise and causes the engagement ofits clutch ring 65 with casing 64. thereby moving it clockwise ahead ofshaft I, while sector 13 unlocks its clutch ring 86 from casing 84 andwithdraws it in counterclockwise direction. Thus the two sectors I2 andI3 alternately advance and retard and alternately thereby move thecasing 84 of control wheel 58 and thereby the control wheel itselfbecomes zero andthe eccentric rings 11 and I8 do not move theirrespective sectors I! and 13.

Both sectors in this case take their "respective clutch rings 65 and 8along in clockwise direction; both clutch rings engage casing 84 andthereby move the control wheel 88 at the speed of the driving shaft. Inthiscase the driven shaft will rotate at the same speed as the driv ingshaft; in other words, the whole gear system rotates as a unit about theaxis of the driving and driven shafts and no parts within the gearsystem move relatively to one another. The. transmission is in highgear. If sliding block 82 in Figure 3 is gradually moved fromthee'xtreme right-hand position toward the left, the eccen-'- tricity ofeccentric diso'rl! increases and thus sectors I2 and I3 commence toadvance control wheel 58 ahead of the driving shaft speed, dependingupon the 'extent of the eccentricity, whereby the driven shaft runsslower and slower until at about the middle position of sliding blocklithe control wheel 88 runs ahead ofydrivamazes ing shaft I at a speedat which the driven shaft l 5 stands still. The gear is in neutral. Ifblock 82 is shifted further to the left, for instance into the positionshown in Figure 3, the eccentricity of disc I! is at a maximum andcontrol wheel 58 runs its maximum amount ahead of driving shaft Iwhereby the driven shaft is moved in reverse direction. The gear is inreverse.

I claim:- y

l. A planetary gear drive between a driving and a driven shaft, having asun gear wheel mounted on thedriven shaft, planetary gear wheels in meshwith saidsun wheel and operated by. the driving shaft to'rotate aroundsaid sun wheel and a control gear wheel in mesh with and surroundingsaid planetary gear wheels and means for operating said control gear atvarying speeds with respect to the driving shaft, said means comprisinga pair of overrunning clutch rings disposed to'engage said control gearwhen rotating in the same direction as the latter and to becomedisengaged when rotated in opposite direction, and means actuated by thedriving shaft for alternately advancing each clutch ring in the drivingdirection a desired angular degree and simultaneously retarding theother ring to the same degree in the other direction.

2. A planetary gear drive between a driving and a driven shaft, having asun gear wheel mounted on the driven shaft, planetary gear wheels inmesh with said sun wheel and operated by the driving shaft to rotatearound said sun wheel and a control gear wheel in mesh with andsurrounding said planetary gear wheels and means for operating saidcontrol gear at varying speeds with respect to the driving shaft, saidmeans comprising a pair of overrunning clutch rings disposed to engagesaid control gear when rotating in the same direction as the latter andto become disengaged when rotated in opposite direction, and meansactuated by the driving shaft for alternately advancing each clutch ringin the driving direction a desired angular degree and simultaneouslyretarding the other ring to the same degree in the other direction, andmeans controllable from outside for varying the degree of advance ofsaid rings.

3. A planetary gear drive between a drivingv and a driven shaft, havinga sun gear wheel mounted on the driven shaft, planetary gear whengotating in the same direction as thelatter and to become disengagedwhen rotated in opposite direction, a gear sector for each clutch ringpivotally mounted on the driving shaft and mesh -.sector advancesalterately its appertaining clutch ring anguiarly with respect to thedriving shaft, and pinions geared between said clutch rings and mountedon said driving shaftjto bodily rotate therewith, said pinions causingthe clutch ring advanced by a high point of the cam to simul- 2,126,294taneously retard the other clutch ring to the same degree to throw thecam roller of the gear sector forsaid other ring onto the cam low pointof said cam body which is in radial alignment surrounding said planetarygear wheels. and

means for operating said control gear at varying speeds with respect tothe driving shaft, said means comprising a pair of overrunning clutchrings disposed to engage said control gear when rotating in the samedirection as the latter and to become disengaged when rotated inopposite direction, a gear sector for each clutch ring pivotcam body anda cam roller on each sector disposed to engage the cam surface of saidbody, said cam body being designed to rock said sectors alternately ontheir own pivots when the driving shaft rotates and the sector rollerspass overa high point of the cam body, so that each sector advancesalternately its appertaining clutch ring angularly with respect to thedriving shaft, and pinions geared between said clutch rings and mountedon said driving shaft to bodily rotate therewith, said pinions causingthe clutch ring advanced by a high point of the 'cam to simultaneouslyretardthe other clutch ring to the same degree to throw the cam rollerof the gear sector for said other ring onto the cam low point of 1 saidcam body which is in radial alignment with that roller, said cam bodyhaving a circumferential cam contour which varies in height in thedirection of the longitudinal cam axis, and means for longitudinallyshifting said cam body to vary the degree of advance of said clutchrings.

5. A planetary gear drive between a driving and a driven shaft, having asun gear wheel mounted on the driven shaft, planetary gear wheelsin'mesh with said sun wheel and operated by the driving shaft to rotatearound said sun wheel and a control gear wheel in mesh with andsurrounding said planetary gear wheels and means for operating saidcontrol gear at varying speeds with respect to the driving shaft, saidmeans comprising a pair of overrunning clutch rings disposed to engagesaid control gear when rotating in the same direction as the latter andto become disengaged when rotated in opposite direction, a gear sectorfor each clutch ring pivotally mounted to rotate bodily with the drivingshaft and meshing with its appertaining clutch .ring, a stationaryeccentric disc surrounding said driving shaft, two 'eccenter ringsindependently rotatably mounted on said disc, each ring being pivotallyattached tov one of said gear sectors to rock its sector on its ownpivot alternately in opposite direction with respect to the other sectorwhen the driving shaft rotates, so that each sector advances and retardsalternately with the other,

sector its appertaining clutch ring angularly with respect to thedriving shaft, whereby each clutch extent determined by the rockingmotions of said sectors.

6. A planetary gear drive between a driving an a driven shaft, having asun gear wheel mounted on the driven s haft, planetary gear wheels inmesh with said sun wheel and operated by the.

driving shaft to rotate around said sun wheel and a control gear wheelin mesh with and suring with its appertaining clutch ring, a stationaryeccentric disc surrounding said driving shaft, two eccenter ringsindependently rotatably mounted on said disc, each ring being pivotallyattached to one of said gear sectors to rock its sector on its own pivotalternately in opposite direction with respect to the other sector whenthe driving shaft rotates, so that each sector advances and retardsalternately with the other sector its appertaining clutch ring angularlywith respect to the driving shaft, whereby each clutch ring alternatelywith the other ring is engaged with and from said control gear and thecontrol gear is rotated ahead of the driving shaft to an extentdetermined by the rocking motions of said sectors, and means for varyingthe eccentricity of said disc with respect to the driving shaft axis tovary the rocking motions of said sectors. i

7. A planetary gear drive between a driving and a driven shaft, having asun gear wheel mountedon the driven shaft, planetary gear wheels in meshwith said sun wheel and operated by the driving shaft to rotate aroundsaid sun wheel and a control gear wheel in mesh with and surroundingsaid planetary gear wheels and means for operating said control gear atvarying speeds with respect to the'driving shaft, said means comprisinga pair of overrunning clutch rings disposedto engage said control gearwhen rotating in the same direction as the latter and to becomedisengaged when rotated in opposite direction, a gear sector for eachclutch ring pivotally mounted to rotate bodily with the driving shaftand meshing with its appertaining clutch ring, a stationary eccentricdisc surrounding said driving shaft, two eccentero rings, independentlyrotatably mounted on said disc, each-ring being pivotally attached toone of said gearsectors to rock its sector on its own pivot alternatelyin opposite direction with respect to the other sector when the drivingshaft rotates, so that each sector advances and retards alternatelywith'the other sector its appertaining clutch ring angularly withrespect to the driving shaft, whereby each clutch ring alternately withthe other ring is engagedwith and from said control gear and the controlgear is rotated ahead of the driving shaft to an extent determined bythe rocking motions of said sectors, a normally stationary slidingblockfor supporting said eccentric disc and being designed to vary theeccentricity of said disc with respect .to the driving shaft axis whenslidingly moved in axial direction, to vary the rocking motions of saidsectors.

' AUGUST TIMMERMANN.

